The invention relates to pneumatic valves.
In some applications for pneumatically actuated equipment, it is desirable for pneumatic control valves used to connect and disconnect a source of compressed air to the equipment to have a slow start characteristic, meaning that there is a gradual increase in pressure when first turned on. It is known in the prior art to adjust the rate of increase of pressure during the slow start period through the use of a needle valve. In some applications it is also desirable to have quick exhaust of the system pressure when a valve has been turned off. The combined features of slow start and quick exhaust have been provided by using a slow start valve with a quick exhaust valve or by constructing a combination valve that has both features built in to it.